ComScore said in the three-month ended in May, that 49.1 million people in the U.S. owned a smartphone, up 8.1 percent from the previous three months. The top of the rankings were led by RIM (NSDQ: RIMM), Apple (NSDQ: AAPL) and Microsoft (NSDQ: MSFT), and although Google came in fourth, it was the only platform to increase its market share—and it soared by 4 percentage points.

With the market moving so quickly, things are bound to change. The survey was conducted before Apple’s latest iPhone 4 was released in June. Also, look for Google to exceed Microsoft’s share in the next period since it is trailing by a minuscule .2 percent.